Double Bass bridge feet corners -- how flat?

[bonaventura]

I've spent a couple of days working on my new bridge. I used the lipstick method described in the TB threads here, and got the feet to fitted so they are about an 80% match for the curve of the top of the bass, i.e. 80% of the feet bottoms are covered with lipstick at this point.

Is 80% enough, or will there be problems with the sound? The one spot that makes me ask the Bass Community about this is the corners of the feet are a bit rounded up.

If anyone has had experience fitting a bridge, please give me your advice here. There is still enough wood left to scrape the whole surface down another few mm without going too far.

Thanks in advance for comments...

 

[1st Bass]

It should all fit.

You might try carbon paper instead of lipstick-- same principle, less messy.

You want a full, airtight fit. It does take practice...and it can be pretty frustrating, until you have mastered it.

 

[Bob Branstetter]

It should all fit.

You might try carbon paper instead of lipstick-- same principle, less messy.

You want a full, airtight fit. It does take practice...and it can be pretty frustrating, until you have mastered it.

I used carbon paper for many years, but I think that the lipstick method is far superior since you do not have to move the bridge to get the lipstick to transfer.

bonaventura - like 1st Bass, I would advise you to keep working on it. 20% is quite a bit to not be in contact with the top.

 

[KSB - Ken Smith]

What tool or tools are you using to fit the feet cutting away the parts that touch little by little?

When I got back into selling Basses a short while ago I brought in 6 new Basses and had to cut the feet of 6 Bridges. I used a red grease pencil and my old Knife with rosewood handle. "Where's the sharpening stone?" I called out the the guys in the shop when I realized how dull my knife was and what lied ahead of me. After the 2nd one things got easier. Still, it's a job I hate doing. Boy were my hands sore after those 6 Bass set-ups.

This is not my knife but it looks somewhat like it;

 

[bonaventura]

What tool or tools are you using to fit the feet cutting away the parts that touch little by little?

First, thanks to you all for responding.

I mainly used a Victorianox all purpose tool with lots of blades. Sort of a mega-Swiss Army knife.

I was slicing more than scraping at first, with the toothed blade (very sharp and good for whittling it down close to the line). Then I switched to a long plain blade, very sharp and good for scraping, but it is not as flat edged, I mean, straight as yours. It curves a bit like all pocket knife blades. I guess I need to get a very flat straight edged blade, right?

Bob, how thick do you put the lipstick on? I mean, on the bass ? I put it on pretty thick and of course then it squishes the whole foot bottom red. That would be cheating myself, I guess, to think that was accurate.

And isn't it harder to get lipstick more consistently even? Carbon paper is going to be exactly even all across and not too thick.

Thanks again for the comments.

Bill

 

[Bob Branstetter]

Bob, how thick do you put the lipstick on? I mean, on the bass ? I put it on pretty thick and of course then it squishes the whole foot bottom red. That would be cheating myself, I guess, to think that was accurate.

And isn't it harder to get lipstick more consistently even? Carbon paper is going to be exactly even all across and not too thick.

Thanks again for the comments.

Bill

I just paint on a thin layer with the lipstick and then use a finger and even out the lipstick layer. (Don't forget to wipe your finger before you pickup up the bridge )
Then just press the bridge down firmly where it normally sits. It doesn't take much of the lipstick if you have removed all or most of the previous lipstick footprint from the bridge foot. If the layer is too thick, you lose detail.

 

[Damon Rondeau]

I really like using this knife from Lee Valley:

[Invalid or Expired Link Removed]

[Invalid or Expired Link Removed]

It's the Beebe Bent Knife. The bend and the size are great for working underneath the feet.

I use a little curved scraper to clean it up just right.

 

[Silversorcerer]

I used two Flexcut knives to carve my bridge, a mini-pelican, and a detail knife. The pelican was real good for removing small irregular shaped high spots and the detail is great for straightening and evening out rough areas, and extending the legs down into the thick part of the feet.

You want to get it so that you can't get a thin piece of paper between the bridge and top anywhere around the edges. I think I got mine much more than 80% contact. The ideal is perfect, the practical is how much time you have between gigs/rehearsals to get the fit as close as possible.

 

[bonaventura]

What tool or tools are you using to fit the feet cutting away the parts that touch little by little?

I really like using this knife from Lee Valley: ... It's the Beebe Bent Knife. The bend and the size are great for working underneath the feet. .. I use a little curved scraper to clean it up just right.

I used two Flexcut knives to carve my bridge, a mini-pelican, and a detail knife. The pelican was real good for removing small irregular shaped high spots and the detail is great for straightening and evening out rough areas, and extending the legs down into the thick part of the feet.

Just to talk a bit about good tools for a sec. And thanks to you all for telling me what you use...

Do you Bob, Ken, Damon, Sorcerer, think a curved blade is ideal for the fine scraping needed at the phase I'm at now (2 or 3 mm max to go)?

I looked in the website of Thomas Flinn & Co. Invalid Link Removed and found the tool Ken took a picture of, it's called Crown Parting Tool 244A and there's another called the Crown Square End Scraper that is flat and used for finishing fine woodworking.

I'm just wondering if too much of a curved blade at this point won't give me the flat edge I need to rely on.

Thoughts?

 

[Bob Branstetter]

You don't need anything special for scraping. I use a sharp knife which I ground a slight curve in blade. Sorry, but I can't send a photo with the iTouch (my laptop is sick today).

 

[Damon Rondeau]

I would venture a guess, bv, that Bob's maybe fit more bridges than anyone else on this board. On a thing like this his opinion is a gorilla and I'm a little kitten....

As for curved cutting tools, any of the woodworking tool vendors (Woodcraft, Lee Valley, etc.) can sell you a curved-edge scraper for pretty cheap dough.

I suspect people who have done a lot of bridges put emphasis on getting a good, clean, accurate starting cut, most likely with a bandsaw. If the first cut is really good, there won't be too much of the hand-tiring scraping and fitting work. My first set of bridge feet took me something like six or seven hours of fitting!

 

[Bob Branstetter]

I don't know about me fitting more bridges than anyone else on this board, but Damon is right on about the importance of the initial cut with a bandsaw or scroll saw. That cut also helps set the bridge angle at 90 degrees.

 

[bonaventura]

I don't know about me fitting more bridges than anyone else on this board, but Damon is right on about the importance of the initial cut with a bandsaw or scroll saw. That cut also helps set the bridge angle at 90 degrees.

I am fitting a Despiau. Pretty nicely cut at about 90 degrees already. But don't you want the bridge to tilt about 1° or so toward the tailpiece to resist warping?

 

[Bob Branstetter]

I am fitting a Despiau. Pretty nicely cut at about 90 degrees already. But don't you want the bridge to tilt about 1° or so toward the tailpiece to resist warping?

If you can see one degree difference when it's on the bass then you're better at it than me. If you straighten the bridge position on your bass periodically, then it shouldn't make any difference if it is cut a couple of degrees off one way or the other as far as warpage is concerned. While your bridge may have been cut at 90 degree (almost any brand bridge I know of will be 90) when it came from the factory, odds are that it won't be by the time you've removed the wood to fit the feet with your knives and scrapers.

 

[1st Bass]

Some of the "intermediate" work can be kept at 90 degrees, by using a drum or spindle sander. I got one of the cheap Ryobi bench-top spindle-sanders several years ago, and I love it.

I make my scrapers out of blue-tempered watch-spring, usually, but my favorite was an old, good-quality putty-knife, and I think a really good source is the blade out of one of the wide drywall-mudding knives. You can go to a second-hand tool store and get a blade that is very thin, hard, and springy, and 4" x 12".

Cut the rough shape out with tin-snips, grind it to final shape with a bench grinder, then sharpen, hone and burnish in whatever school of thought you are comfortable.

 

[Silversorcerer]

I suspect people who have done a lot of bridges put emphasis on getting a good, clean, accurate starting cut, most likely with a bandsaw. If the first cut is really good, there won't be too much of the hand-tiring scraping and fitting work. My first set of bridge feet took me something like six or seven hours of fitting!

For those cuts, I used a large X-acto razor saw that is like a mini-dovetail saw. I haven't done many bridges, but this saw works well for the frequency that I do them. If I were doing a large volume of this type of work, I would probably set up a different motorized saw for the job.

To me 2-3mm is still quite a bit of wood left to remove. At that point I'm still taking out some "slices". I use both the curved (pelican) and straight (detail) at this point alternating between the two, deepening with the curved blade, then evening out across the foot with the straight one. At about 0.5 mm, then I start scraping areas that take the crayon. I used my old Gerber pocket knife sharpened real well for the scraping part of the process.

As far as the lean of the bridge goes, a bridge viewed from the side is a vertical wedge that should have 90 degrees between the surface facing the tail piece and the top. The angle between the top bridge surface (toward fingerboard) and the top will be more than 90 degrees depending on how wedge shaped the bridge is. Some are thicker at the feet than others.